Skin cancer danger without the sun
Fair-skinned people with red hair may be at risk of developing the potentially deadly skin cancer melanoma even if they stay out of the sun, a new study in mice suggests.
Researchers working on the study think they have found that the pigment that gives hair its red hue may have cancer-causing effects just by itself.
The news is a double whammy for pale-skinned redheads, who are also more vulnerable than others to the sun's ultraviolet (UV) rays.
“There is something about the redhead genetic background that is behaving in a carcinogenic fashion, independent of UV,” Massachusetts General Hospital cancer biologist David Fisher, who led the research, told the journal Nature where the study was published today.
“It means that shielding from UV would not be enough.”
But Eugene Healy, a clinical dermatologist at the University of Southampton in Britain, sought to avoid alarming those who might be affected.
“Whatever risk was there, was always there. But we don’t see lots of spontaneous melanomas in redheads. We shouldn’t be sending out a worrying message for them," Nature reported him saying.
People with fair, freckly skin and red hair produce a red–yellow form of the pigment melanin, called pheomelanin, which is less effective at protecting the skin from UV damage than the darker form, eumelanin. The difference is caused by a genetic mutation.
The researchers looked at how melanomas develop in mouse models of olive-skinned, ginger and albino colouring, with the last group having the same genetic background as the dark-skinned mice but lacking the enzyme needed to synthesize melanin.
The researchers also tweaked each group’s genes to be more susceptible to developing benign moles, which Fisher said was a probable first step in the development of melanoma.
Before the researchers even exposed the mice to UV light, about half the ginger mice had developed melanomas.
The result suggested the pigment itself was a cause of melanoma, with the researchers proposing the increased melanoma risk could have something to do with the pigment-production process, or a by-product of it, in melanin-containing cells called melanocytes.
Interestingly, a study published by Healy in 2010 suggested the red–yellow pheomelanin form of melanin was protective against the effects of UV radiation in another type of skin cell.
In a comment carried by Nature, US cancer researchers Mizuho Fukunaga-Kalabis and Meenhard Herlyn said research was needed into drugs that may induce production of the darker form of melanin, called eumelanin, or boost cancer-protecting antioxidants.